IRLF 


SB    Eh    Dfll 


UM  CLEANING 
ENGINEERING 


E.   JT.   MOORE 


Fuller  Publishing  Company 


Portland    SEATTLE: 


HAND  BOOK 


ON 


VACUUM  CLEANING 
PLANTS 


TREATISE  FOR  THE  USE  OF 
ARCHITECTS 


Drawing  Specifications  for  Cleaning 
Plants 


Copyright  1912 

By    ,    \\\ 
E.  J.   MOORE. 


Press  of  the 

Gateway  Printing  Company 
Seattle 


v 


DEDICATION 


Realizing  that  little  data  has  been  placed  before  the  public  on  the 
subject  of  Vacuum  Cleaning  Devices,  the  author  has  had  prepared  a 
small  treatise  on  the  subject,  and  in  presenting  it  to  the  public  with 
the  hope  it  may  prove  of  value,  he  dedicates  it  to  the  architectural 
profession  of  the  Greater  Northwest  as  being  the  one  most  vitally 
interested  in  the  science  and  practice  of  air  cleaning. 


*  »» 
y* 


HAND  BOOK  ON  VACUUM  CLEANING 


FOR    COMPARING    AND    DRAWING    SPECIFICATIONS. 

As  there  are  several  classes  of  vacuum  cleaning  apparatus  on  the 
market  it  is  advisable  to  describe  the  principles  of  operation  and  gen- 
eral construction  of  the  various  types  and  establish  a  standard  rating 
in  order  to  secure  the  desired  capacity  in  the  plant  selected  for  given 
conditions  and  to  reduce  the  required  plant  to  a  definite  capacity 
rather  than  to  take  miscellaneous  ratings. 

Capacity — The  Main  Consideration  in  Selecting  a  Vacuum  Clean- 
ing Plant  is  to  determine  on  A  Standard  Capacity.  By  this  is  meant 
the  Amount  of  Air  to  Be  Drawn  Through  Each  Renovator  (figured  in 
cubic  feet  per  minute),  and  also  The  Vacuum  to  Be  Maintained  to  ac- 
complish the  desired  results. 

No  two  vacuum  systems  on  the  market  use  the  same  standard  of 
capacity  in  making  quotations,  some  makers  bidding  on  equipment 
two  to  three  times  larger  than  others.  Even  Though  They  Are  Rated 
the  Same  Sweeper  Capacity,  therefore  the  engineer  should  determine 
what  in  his  opinion  constitutes  the  proper  standard  of  capacity  and 
then  select  a  plant  or  call  for  proposals  on  a  .plant  of  a  Specified  Air 
Displacement  and  Vacuum.  This  will  compel  all  makers  to  bid  on  the 
same  equipment  and  will  assure  the  purchaser  of  getting  exactly  what 
he  contemplates.  • 

Before  proceeding  further,  we  will  consider  the  principles  of  opera- 
tion of  a  vacuum  cleaning  system  and  the  various  functions  which 
are  performed,  and  later  discuss  the  various  features. 

Principle  of  Operation — The  vacuum  cleaning  system  consists  pri- 
marily of  an  exhauster  or  vacuum-producing  machine  which  is  to  create 
a  partial  vacuum  in  a  piping  system,  thereby  causing  air  to  rush  into 
the  pipes  to  fill  the  void  and  in  rushing  into  the  pipes,  carry  the  dirt 
along  with  it. 

In  a  commercial  unit,  the  building  is  piped  with  one.  or  more  ver- 
tical pipes,  or  "Risers,"  running  from  basement  to  top  floor  and  con- 
nected together  at  the  basement  or  lowest  floor  and  carried  to  the 
location  of  the  pumping  plant.  The  cleaning  appliances  are  connected 
to  lengths  of  hose  which  are  in  turn  connected  to  inlets,  or  valves, 
situated  on  each  riser  at  each  floor,  the  openings  coming  out  at  con- 
venient points,  usually  in  the  baseboard.  This  piping  system  is  not 
connected  to  the  vacuum  pump,  however,  as  in  that  case  all  the  dirt 
would  enter  the  pump  and  cause  damage,  therefore  the  pipe  line 
carrying  the  dirty  air  is  carried  direct  to  the  dirt  collector  or  "Sep- 
arator," and  after  passing  through  this  tank  and  becoming  purified 
the  air  passes  to  the  exhauster  or  vacuum  producer  and  thence  through 
the  exhaust  to  a  vent,  either  up  a  flue  or  to  the  outside  of  the  building. 


268947 


VACUUM  CLEANING  ENGINEERING 


Operating  handles  are  provided  of  suitable  design  to  render  the 
sweeping  easy  and  convenient  and  the  handles  are  usually  provided 
with  valves,  permitting  the  air  flow  to  be  shut  off  as  soon  as  the  work 
is  completed  by  one  operator,  thereby  increasing  the  action  at  the 
other  sweepers  still  in  operation,  decreasing  power  consumption. 

A  system  of  vacuum  regulation  is  also  required  enabling  the  opera- 
tor to  maintain  any  desired  vacuum  required  for  his  particular  work. 

COMPONENT  PARTS— VARIOUS  TYPES— VACUUM  PRODUCERS. 
Double  Acting  Reciprocating  Type — The  Double  Acting  Reciprocat- 
ing Vacuum  Pump  is  the  most  efficient  and  also  the  most  expensive 
to  build.  This  type  is  built  on  the  same  lines  as  a  standard  air  com- 
pressor, the  piston  being  an  airtight  fit  in  the  cylinder  and  provided 


Horizontal  Reciprocating*  Vacuum  Pump  Motor  Driven. 

with  rings  to  prevent  leakage  and  take  up  all  wear.  The  piston,  in 
vacuum  work,  should  travel  very  close  to  the  cylinder  head  in  order 
to  force  out  all  the  air  and  eliminate  an  air  cushion  which  would 
expand  on  the  return  stroke  and  cause  loss  in  efficiency.  The  piston 
usually  travels  to  within  1/16  inch  of  the  heads  and  the  valve  chambers 
are  made  as  small  as  possible,  at  the  same  time  allowing  large  air 
ports  for  the  passage  of  the  air.  The  double  acting  type,  as  its  name 
indicates,  is  a  pump  that  performs  work  on  both  sides  of  the  piston, 
that  is,  while  the  piston  on  one  side  is  forcing  out  the  air  from  the 
cylinder,  it  is  drawing  air  into  the  cylinder  on  the  other  side  and  on 
the  return  stroke  the  operation  is  reversed. 

A  double  acting  pump  has  twice  the  capacity  of  a  single  acting 
pump  of  the  same  bore  and  stroke,  and,  as  the  piston  friction  remains 
the  same  in  either  case,  the  double  acting  type  has  an  added  efficiency 
over  the  single  acting  type  exactly  equal  to  the  piston  friction  of  one 


VACUUM  CLEANING  ENGINEERING 


Double  Acting  Reciprocating  Pump  Oscillating-  Valves   (Cross  Section). 

cylinder  and  its  valves,  as  the  single  acting  type  has  the  friction  of 
two  pistons  and  two  sets  of  valves  to  give  the  same  result. 


Cross  Section  of  Horizontal  Reciprocating-  Pump. 

The  double  acting  type  has  almost  half  the  number  of  working 
parts  and  consequently  has  less  inertia  to  overcome  and  takes  up  less 
floor  space. 

Single  Acting  Reciprocating  Pump  is  the  next  in  efficiency  and  is 


VACUUM  CLEANING  ENGINEERING 


of  the  same  construction  as  the  double  acting  pump  except  that  it 
uses  only  one  side  of  the  piston  and  therefore  has  only  half  the  ca- 
pacity of  a  double  acting  type  of  the  same  cylinder  dimensions. 


Cross  Section  Double  Acting1  Cylinder  Showing*  Oscillating*  Valves. 

Mechanically  Operated  Valves — The  efficiency  of  the  reciprocating 
pump  may  be  increased  by  the  use  of  mechanically  operated  intake 
and  exhaust  valves.  These  are  usually  of  the  oscillating  type  and 
utilize  a  cylindrical  valve  having  large  ports,  which,  as  they  oscillate 


Oscillating  Valve  Mechanism. 

from  a  neccentric  movement,  alternately  connect  the  cylinder  with  the 
inlet  and  exhaust  manifolds.  By  this  method  the  pump  is  noiseless  in 
its  operation  and  the  internal  compression  necessary  to  force  open 


VACUUM  CLEANING  ENGINEERING 


spring  poppet  valves  is  eliminated,  permitting  the  pump  to  work  at 
low  temperature  without  a  water  jacket. 

All  piston  pumps  are  of  course  provided  with  at  least  two  and 
sometimes  three  sets  of  rings  on  the  piston,  the  laps  in  the  rings  be- 
ing spaced  apart  on  the  circumference  of  the  piston  so  that  the  joints 
will  not  work  together  and  cause  leakage. 

Single  acting  pumps  are  seldom  used  in  present  day  construction 
as  the  cost  of  construction  is  about  the  same  as  double  acting  and 
they  are  not  as  efficient,  compact  or  light  as  the  double  acting  type. 

Rotary  Exhausters  are  built  in  several  types.  They  are  the  cheap- 
est type  to  build  and  are  usually  run  at  comparatively  high  speeds. 
The  rotaries  are  most  efficient  on  low  vacuums  (up  to  10  inches  of 
mercury),  but  above  this  point  they  have  a  tendency  to  leak,  run  hot 
and  require  an  excess  of  oil,  or  are  limited  to  short  runs  with  stop- 
pages for  cooling. 


Two   Impeller  Rotary. 

Two  Impeller  Type  Rotary  is  the  type  usually  required  when  ro- 
taries are  called  for,  as  their  internal  friction  is  much  less.  This  type 
consists  of  an  eliptical  shell  in  which  are  two  revolving  members 
shaped  something  like  a  dumb-bell  (see  cut)  which  revolve  towards 
each  other,  but  without  quite  touching,  leaving,  however,  only  a  minute 
space  between  impellers  which  is  supposed  to  be  taken  up  by  a  film 
of  oil.  The  revolving  of  these  impellers  successively  draws  in  the 
air  and  forces  it  out  and,  from  its  simplicity  and  fewness  of  parts, 
is  the  most  desirable  type  of  rotary.  Its  efficiency,  however,  is  not  par- 
ticularly high  and  it  is  hardly  practicable  where  high  vacuum  is  re- 
quired on  account  of  the  dead-air  space  that  always  exists  in  the 
cylinder. 


VACUUM  CLEANING  ENGINEERING 


Positive  Displacement  Rotary  consists  of  a  cylindrical  shell  in 
which  is  placed  a  cylinder  or  drum  of  smaller  size  which  is  eccentric 
to  the  main  cylinder,  that  is,  the  circumference  of  the  small  drum  will 
touch  the  inner  side  of  the  cylinder,  leaving  a  crescent  shaped  space 


Vane  Type  Rotary. 

between  the  two.  In  the  drum  are  several  sliding  vanes  which  are 
held  out  against  the  inside  of  the  cylinder  as  the  drum  revolves,  and 
these  vanes  force  the  air  out  of  the  crescent  shaped  space  on  one 
side  and  draw  it  in  on  the  other  side. 

Turbine  Type — This  is  merely  a  blower,  consisiting  of  a  large  num- 
ber of  vanes  on  the  impeller,  or  is  a  fan  which  is  run  at  high  speed 
and  creates  a  suction  of  a  Large  Volume  of  Air  but  at  a  Very  Low 
Vacuum.  The  turbines  maintain  under  ordinary  working  conditions 
a  vacuum  of  1^  to  3  inches  of  mercury.  , 

They  are  best  adapted  to  bare  floor  sweeping,  as  the  vacuum  is 
not  sufficient  to  remove  tenacious  material  from  a  carpet,  such  as 
threads,  fluff,  hair  combings,  etc. 

The  fan  type,  on  account  of  its  low  vacuum,  requires  about  300% 
larger  pipe  area  for  its  use  and  the  size  of  the  hose  has  to  be  pro- 
portionately increased.  A  turbine  usually  employs  a  hose  of  2-inch 
internal  diameter  for  short  runs  and  for  long  runs  a  section  of  2%- 


VACUUM  CLEANING  ENGINEERING 


inch  hose  next  the  riser  and  reducing  half  way  to  2-inch.  The  high 
vacuum  systems  require  only  l^-inch  hose  in  any  length  up  to  150 
feet,  providing  they  employ  over  12  inches  of  vacuum,  and  the  ease 
in  handling  a  small,  light  hose  is,  of  course,  an  advantage,  and  a  sav- 
ing in  the  maintenance  cost.  A  turbine  is  practically  identical  in  its 
operation  to  a  planing  mill  exhauster  for  shavings  in  saw  mills,  with 
which  everyone  is  doubtless  familiar.  The  fan  type  is  inapplicable 
for  portable  work  as  its  vacuum  is  too  low  to  allow  washing  or  cleaning 
the  air  and  all  fine  dust  is  blown  back  into  the  room. 

Injector  Type — A  vacuum  may  be  obtained  by  an  injector  system 
such  as  used  for  supplying  feed  water  to  a  steam  boiler  and  operated 
either  by  steam  or  compressed  air.  Injectors  for  vacuum  cleaning 
are,  however,  very  inefficient,  and  are  not  justifiable  unless  steam 
costs  practically  nothing.  , 

The  operation  of  an  injector  system  under  ordinary  conditions  costs 
at  least  three  times  that  of  a  mechanically  operated  exhauster,  and 
even  at  a  low  first  cost,  proves  a  very  expensive  device  to  operate. 

This  type  of  apparatus  is  now  practically  obsolete. 

Separators. 

A  separator  system  to  be  of  the  greatest  efficiency,  should  offer  the 
least  possible  resistance  to  the  air  current — should  effectively  separate 
the  dust  and  dirt  from  the  air  and  deliver  it  pure  to  the  pump;  should 
have  the  least  number  of  parts  subject  to  wear  and  requiring  atten- 
tion or  replacement  and  should  be  accessible  on  the  interior  by  suit- 
able hand-hole  plates  or  covers  and  preferably  a  point  in  the  tank 
where  it  can  be  entered  if  necessary.  The  most  satisfactory  type 
of  separator  is  one  embodying  the  above  features  and  requiring  little 
attention,  the  discharge  of  the  dirt  being  automatic  or  semi-automatic 
in  action. 

Automatic  Separators  are  of  the  wet  separator  type  and  are  ar- 
ranged to  effectually  mix  the  incoming  dirty  air  with  water,  depositing 
all  the  dirt  in  the  water  and  then  by  means  of  baffle  plates  removing 
the  superfluous  moisture  from  the  air. 

These  automatic  separators  are  designed  to  slowly  fill  with  water 
while  the  vacuum  is  on  until  the  water  in  the  tank  reaches  a  fixed 
level,  at  which  point  a  float  trips  a  valve  and  the  pump  is  cut  off 
from  the  separator,  the  vacuum  on  the  system  broken  and  the 
contents  of  tank  is  drained  to  sewer.  When  float  reaches  the  low 
water  level,  the  valve  should  be  tripped  back  into  the  operating  posi- 
tion and  the  performance  repeated.  The  tank  should  discharge  its 
water  to  sewer  in  about  20  seconds.  A  drain  should  also  be  taken 
from  the  bottom  of  tank  to  insure  cleaning  out,  by  flushing,  any  de- 
posit which  might  collect  in  the  bottom  of  the  tank.  There  should 
also  be  means  in  the  bottom  of  tank,  where  the  air  enters  under 
water,  for  breaking  the  air  current  up  into  finely  divided  portions  in 
order  that  all  portions  may  come  in  contact  with  the  water  and  be 


10 


VACUUM  CLEANING  ENGINEERING 


thorougtly  purified.  There  are  No  Bags,  Screens  or  other  obstructions 
in  this  type  of  apparatus,  the  water  being  the  only  purifying  medium 
and,  if  the  area  of  inlet  pipe  is  sufficient,  there  will  be  no  resistance 
from  the  water,  as  the  air  bubbles  will  rise  of  their  own  buoyancy. 


Automatic  Type  Separator. 

This  is  a  most  satisfactory  type  and  is  adaptable  also  for  Wet  Scrub- 
bing by  Vacuum,  as  the  floors  after  being  scrubbed  can  be  run  over 
with  a  vacuum  squeegee  brush  and  all  the  moisture  drawn  off  the  floor 
and  down  into  the  separator  tank.  In  this  process,  however,  the  hose 
end  should  be  placed  in  fresh  water  after  the  cleaning  is  complete 
and  about  ten  gallons  of  clear  water  drawn  down  the  hose  and  pipes 
to  clear  the  dirty  water  and  then  allowed  to  draw  air  for  a  few  min- 
utes to  dry.  A  solution  of  lye  should  be  run  through  the  pipes  once 
a  week,  followed  by  clear  water. 

Spiral  or  Cyclone  Type  of  Separators  are  of  the  same  efficiency 
as  the  automatic,  the  only  difference  being  that  two  tanks,  each  of  the 
size  of  the  automatic,  are  required,  one  being  the  dry-tank  which  re- 
ceives about  90%  of  the  dirt,  and  the  wet  tank  which  is  operated  on 
the  same  principle  as  the  automatic  except  that  it  does  not  discharge 
automatically  to  sewer.  The  dry  tank  has  an  interior  spiral  partition 
whose  cross  sectional  area  increases  as  the  air  progresses  and  there- 
by slows  the  velocity  of  the  air-current,  at  the  same  time  carrying  all 
particles  in  the  air  toward  the  bottom  of  the  tank.  The  air  flow  be- 


VACUUM  CLEANING  ENGINEERING  11 

comes  very  sluggish  near  the  center  of  the  tank  and  the  dirt  settles 
of  its  own  weight  and  the  fresh  air  passes  up  through  the  central 
tube,  thence  to  the  wet  separator  where  it  enters  under  water  and  the 
remaining  fine  particles  of  dust  are  absorbed.  The  air  then  runs 
against  spiral  baffle  plates  until  all  the  moisture  has  been  deposited 
on  these  plates  and  the  air  goes  to  the  pump  clean  and  dry.  This 
type  has  No  Bags  or  Screens  and  there  is  Nothing  to  Get  Out  of  Order 
or  require  renewal.  The  only  attention  being  required  is  dumping  the 
dry  tank,  which  is  accomplished  by  opening  a  suitable  gasketed  door 
in  the  base  and  allowing  the  dirt  to  fall  out  into  a  bucket  or  recep- 
tacle and  flushing  wet  separator  to  sewer.  These  separators  are  al- 
ways mounted  on  cast  iron  legs  raising  them  about  a  foot  or  eighteen 
inches  from  the  floor. 

This  type  of  separator  is  most  satisfactory  and  efficient. 


Bag*  Strainer. 

Bag  Strainers  are  used  on  many  makes  of  machines  and  are  almost 
invariably  used  on  all  makes  in  smaller  sizes  (usually  from  1  to  3 
sweeper  sizes),  and  consist  of  a  metal  shell  approximately  IVz  feet  in 
diameter  by  4  feet  high  or  equivalent,  into  the  side  of  which  the  pipe 
line  is  brought  and  an  elbow  turned  up,  directing  the  air  blast  against 
a  sheet  metal  dome  or  receptacle  which  deflects  the  air  current  down 
towards  the  bottom  of  the  tank  and  at  the  same  time,  by  the  expansion 


12  VACUUM  CLEANING  ENGINEERING 

of  the  air  in  the  tank,  its  velocity  is  decreased,  therefore  most  of  the 
dirt  falls  to  the  bottom,  while  the  finer  particles  carry  up  with  the 
air  current  which  is  passed  through  a  canvas  or  cloth  sack,  which 
screens  out  the  remaining  dust  particles.  These  sacks,  of  course, 
require  frequent  cleaning  and  beating,  and  hand-holes  are  arranged 
for  that  purpose.  Also  when  sacks  rot  or  become  torn,  the  dirt  carries 
over  to  the  pump  and  chokes  it,  therefore  it  is  customary  to  place  an 
auxiliary  strainer  of  some  sort  (one  having  a  gauze  or  metal  screen), 
between  the  bag-separator  and  the  pump  to  prevent  any  dirt  being 
carried  over  to  the  pump  in  case  of  damage  to  the  sack. 

The  resistance  of  the  sacks  and  particularly  a  deposit  of  dust  over 
the  sack  tends  to  impair  the  vacuum  and  the  efficiency  unless 
the  sack  is  cleaned  at  frequent  intervals,  and  for  this  reason  this  type 
is  hardly  to  be  recommended  in  sizes  larger  than  three  sweeper,  and 
not  larger  than  two  sweeper  if  the  installation  warrants  first  class 
equipment.  The  bag  strainer  is,  of  course,  the  cheapest  type  to  build, 
and  is  generally  used  where  first  cost  is  the  main  consideration. 

In  some  cases  the  bag  strainer  is  used  with  a  wet  tank  also,  but 
this  practice  is  being  gradually  discontinued,  as  a  good  bag  strainer, 
even  though  not  very  efficient,  should  at  least  stop  the  dirt  when  used 
in  conjunction  with  an  auxiliary  strainer. 

Power  Supply — Motors. 

Electric  motors  are  selected  from  the  various  standard  makes  to 
conform  to  the  required  current  supply,  and  should  preferably  run  at 
medium  speeds,  from  900  revolutions  per  minute  (R.  P.  M.)  to  as  high 
as  1,500  R.  P.  M.  on  small  machines,  however,  the  slower  the  speed 
the  longer  life  and  greater  freedom  from  repairs  and  trouble  in  gen- 
eral. Motors  should  be  required  to  carry  full  load  indefinitely  (under 
regular  working  conditions)  without  overheating. 


VACUUM  CLEANING  ENGINEERING 


,  Drives. 

The  most  efficient  and  satisfactory  means  of  driving  the  pump  from 
the  motor  is  worthy  of  consideration  as  it  has  a  decided  effect  upon 
the  permanent  service  of  the  equipment. 


14 


VACUUM  CLEANING  ENGINEERING 


Silent  Chain  Drive  is  the  best  known  drive,  and  is  made  in  several 
types.  These  silent  chains  ars  positive  in  their  action  and  quite 
similar  to  bicycle  or  automobile  chains.  They  are  noiseless  in  their 
action  and  last  indefinitely  with  almost  no  wear,  and  transmit  the 
power  of  the  motor  with  the  least  possible  loss. 


Renold  Silent  Chain. 

The  Link  Belt  Company  builds  the  Renold  Silent  Chain,  a  cut  of 
which  is  shown,  which  illustrates  the  operation  clearly,  also  the 
method  of  inserting  new  links  or  shortening  the  chain.  The  teeth 
mesh  in  special  pulleys  which  are  grooved  to  mesh  perfectly  with  the 
pitch  the  chain  will  assume  in  an  arc  equal  to  the  circumference  of 
the  pulley. 

The  Peerless  V  Chain  consists  of  links  similar  to  bicycle  chain 
covered  with  a  leather  facing.  These  links  have  a  V-shaped  cross 
section  and  fit  into  V-shaped  grooves  in  the  rim  of  the  pulleys  and 
are  wedged  in  as  the  load  is  increased. 

Vacuum   Regulators 
are  of  two  types,  the  vacuum  breaker  and  the  unloader  types. 

Vacuum  Breaker  is  an  inverted  safety  valve.  It  opens  in  towards 
the  pump  when  the  vacuum  reaches  a  determined  point  and  permits 
air  being  drawn  in  through  its  opening  Instead  of  the  Pipe  Line,  until 
the  vacuum  falls  to  the  desired  point.  These  breakers  are  of  two 


VACUUM  CLEANING  ENGINEERING  15 

types,  one  type  consisting  of  a  differential  piston  valve  which  has  an 
adjustment  to  open  the  pipe  line  to  the  atmosphere  at  any  desired 
vacuum  and  a  second  adjustment  to  close  the  vent  to  atmosphere 
when  the  vacuum  falls  to  the  desired  point. 

The  simplest  form  of  breaker  is  merely  a  leather  seated  valve  in 
the  suction  line  which  is  held  in  its  seat  by  a  spring,  with  the  vacuum 
tending  to  pull  it  open  against  the  tension  of  the  spring.  By  varying 
the  tension  of  the  spring  the  valve  can  be  made  to  pull  open  and 
admit  air  when  the  vacuum  on  the  suction  line  reaches  any  desired 
point. 

Vacuum  Unloader  operates  to  best  advantage  on  pumps  having  pop- 
pet discharge  valves  and  performs  its  function  by  cutting  off  the  sue 
tion  line  of  the  vacuum  pump  at  a  point  near  the  pump  so  that  it  can- 
not draw  air  after  the  vacuum  has  reached  a  determined  value.  As 
there  will  be  no  air  drawn  into  the  cylinder,  there  will  be  no  air  to 
force  out  through  the  exhaust,  therefore  the  discharge  valves  will  not 
open  and  the  pump  will  operate  in  a  vacuum  and  no  work  will  be  per- 
formed in  the  cylinder. 

Where  mechanical  valves  are  used  on  the  pumps,  the  breaker  is 
to  be  preferred,  but  where  poppet  valves  are  used  on  exhaust,  the 
unloader  is  the  most  efficient. 

Hose — The  vacuum  hose  should  be  of  a  type  which  will  prevent  col- 
lapsing under  any  vacuum  which  the  machine  is  capable  of  producing, 
and  should  have  an  inner  lining  so  constructed  that  even  though  the 
vacuum  runs  up  to  a  high  point,  the  lining  will  not  pull  loose  and  tend 
to  close  up  the  pipe.  This  is  one  of  the  most  common  difficulties  in 
vacuum  hose.  The  hose  should  be  reinforced  with  wire  and  at  the  same 
time  the  inner  bore  of  the  hose  should  be  smooth,  and  it  is  preferable  to 
have  the  outside  surface  smooth  also. 

The  nipples  of  the  hose  connections  at  each  end  should  have  reamed 
ends  on  a  gradual  taper  so  that  at  the  end  of  the  nipple  there  shall  be 
no  shoulder  to  catch  the  incoming  dirt.  Hose  connections  should  be 
of  standard  hose  thread. 

Metal  Hose  constructed  of  steel  ribbon  wound  spirally  with  locked 
joints  packed  with  rubber,  forms  the  lightest  and  most  flexible  hose 
known. 

This  hose  can  be  had  either  bare  or  with  a  cloth  covering,  the  latter 
being  a  trifle  more  expensive.  The  bare  steel  hose  being  almost 
smooth  on  the  exterior  and  smoothly  finished,  is  not  inclined  to  mar 
furniture  even  though  uncovered,  and  appears  a  satisfactory  hose  to 
use.  The  absence  of  the  cloth  covering  increases  its  flexibility  con- 
siderably. The  surface  of  the  hose  is  galvanized  and  it  can  therefore 
also  handle  water  with  impunity. 

Metal  hose,  if  not  dented  or  sprung,  and  handled  with  ordinary 
care,  has  a  long  life.  The  force  required  to  pull  steel  hose  around 


16  VACUUM  CLEANING  ENGINEERING 

right  angle  bends  is  only  about  one-fourth  that  required  for  rubber 
hose. 

Rubber  Hose  is  most  commonly  used  and  is  generally  in  the  I  or 
1*4 -inch  internal  diameter  size,  which  is  suitable  for  all  systems  em- 
ploying 10  inches  of  vacuum  or  over.  Larger  hose  is  unwieldy  to 
handle  and  is  generally  unsatisfactory  on  account  of  the  hardship  it 
imposes  on  the  operators.  Rubber  hose  is  also  adaptible  for  wet- 
scrubbing,  and  will  handle  water  as  well  as  air.  Rubber  hose  should 
last  about  three  years  with  careful  handling. 

Inlets  or  Hose  Connections  are  of  many  types.  The  most  substan- 
tial and  dependable  is  a  standard  screw  hose  connection.  A  small, 
neat  design  of  male  thread  for  hose  connection  is  provided  and  a 
gasketed  cap  (secured  by  chain)  provided  to  close  the  opening  when 
not  in  use.  These  connections  are  Always  Tight  and  in  general  show 
greater  efficiency  than  the  automatic  types  which  are  held  shut  by 
vacuum.  Hose  connections  should  have  flanges  and  should  not  pro- 
ject from  the  finish  more  than  approximately  2  inches.  The  finish 
should  be  polished  nickel  or  made  to  harmonize  with  the  surrounding 
hardware. 

Flush  Valves  are  used  where  it  is  desired  to  make  a  finished  job 
and  conceal  the  hose  connection.  These  are  made  with  a  neat  metal 
surface,  usually  "circular  in  shape  and  arranged  to  fasten  with  a  simple 
lock.  For  use,  the  cover  is  lifted  up  and  the  hose  inserted.  When  the 
opening  is  closed,  a  pad  of  rubber  attached  to  the  cover  is  drawn 
against  the  seat  and  the  vacuum  draws  it  tight  enough  to  close 
the  opening. 

Requirements   to    Be    Demanded. 

1.  The  machine  should  clean  rapidly  and  thoroughly. 

2.  The  machine  should  preferably  be  capable  of  taking  up  scrub 
water. 

3.  The  machine  should  run  quietly  without  vibration. 

4.  The  machine  should  run  at  low  speed  if  long  wear  is  desired. 

5.  The  machine  should  be  accessible  for  adjustments  and  all  parts 
should  be  renewable  and  interchangeable. 

(1)  For  rapid  cleaning,  it  has  been  demonstrated  by  long  ex- 
perience that  in  commercial  work,  such  as  cleaning  buildings,  or 
wherever  help  is  paid  for  the  purpose  of  cleaning,  a  vacuum  of  at 
least  10  to  12  inches  should  be  maintained  at  the  separator,  and  the 
displacement  of  the  pump  should  provide  for  at  least  75  cubic  feet  of 
air  per  minute  for  each  sweeper  in  use.  Thus,  if  one  wanted  a  plant 
to  permit  three  janitors  to  clean  simultaneously  (known  as  a  three 
sweeper  plant),  an  air  displacement  of  3  times  75,  or  225  cubic  feet  of 
free  air  should  be  required  of  the  pump  with  a  guaranteed  vacuum 
of  10  to  12  inches  of  mercury.  This  will  clean  practically  anything 
which  does  not  have  to  be  literally  scraped  off  the  floor.  Where  long 


VACUUM  CLEANING  ENGINEERING  17 

horizontal  pipe  runs  are  used,  80  to  85  cubic  feet  displacement  per 
sweeper  is  preferable. 

The  vacuum  desired  should  be  specified  at  the  pump  or  at  the 
separator,  for  this  is  always  constant  and  with  given  conditions  to 
start  with  and  proper  piping  system,  the  results  will  always  be  uni- 
form at  the  renovator.  The.  test  for  vacuum  should  be  made  with 
the  required  number  of  sweepers  connected  to  50  or  75  foot  lengths 
of  hose  in  actual  operation  and  the  openings  through  renovators 
should  be  equal  to  one  square  inch  in  area,  except  for  special  work. 

In  preparing  specifications,  it  is  best  to  disregard  the  number  of 
sweepers  in  the  specifications  themselves  and  call  for  air  displace- 
ment in  cubic  feet — found  by  multiplying  75  to  80  by  the  number  of 
sweepers  to  operate  simultaneously.  The  vacuum  should  also  be 
specified  at  not  less  than  10  inches  of  mercury  and  in  this  manner, 
all  types  of  machines  will  bid  on  the  same  identical  capacity  instead 
of  using  their  own  ratings,  which  vary  greatly. 

(2)  At  least  3  h.  p.  should  be  required  for  each  sweeper,  as  this 
power  is  actually  required  to  achieve  the  above  results. 

(3)  The   machine   should   be   quiet  in   operation   and   not  disturb 
those  in  adjoining  rooms.     The  parts  should  be  balanced  and  should 
operate  without  vibration.     In  reciprocating  machines  it  is  preferable 
to  use  mechanical  valves,  which  reduce  noise  and  increase  efficiency 

Chain  drives  should  be  specified  for  quiet  operation  and  efficiency, 
and  chain  guards  should  be  required  to  prevent  clothing  being  caught 
and  the  throwing  of  oil. 

(4)  The  pump  should  run  at  low  speed,  as  the  life  of  the  pump 
is  dependent  upon  the  speed  at  which  it  operates. 

The  piston  speed  of  pumps  should  vary  between  150  and  300  feet 
per  minute  for  ordinary  work,  except  in  residential  plants,  which  may 
run  up  as  high  as  500  feet  per  minute. 

For  commercial  plants,  the  revolutions  per  minute  in  pumps  de- 
signed for  long  life  should  not  exceed  250  revolutions  per  minute. 
This  allows  a  pump  to  carry  its  load  with  ease,  with  little  vibration, 
and  eliminates  loss  in  efficiency  at  the  ends  of  strokes  to  some  extent. 

The  machine  should  not  overheat  from  long  runs  at  full  capacity, 
and  should  be  able  to  operate  for  eight  hours  without  stop,  if  desired, 
without  showing  distress.  The  temperature  of  the  pump  should  keep 
within  safe  limits  and  none  of  the  sliding  or  moving  parts  should 
assume  a  temperature  above  100  degrees  higher  than  the  surrounding 
atmosphere.  , 

(5)  All  parts  of  the  machine  should  be  adjustable.     The  engineer 
or  operator  should  be  able  to  take  up  wear  on  any  moving  part  by 
means  provided  in  the  machine  for  this  purpose,  and  in  a  convenient 
manner. 

All  parts  of  the  machine  should  be  interchangeable  and  removable, 


18 


VACUUM  CLEANING  ENGINEERING 


so  that  in  case  of  a  breakage  or  accident,  a  new  part  may  be  ordered 
from  the  manufacturer  and  fit  into  place  as  the  original  did. 

Means  should  be  provided  for  take-up  of  the  chain  or  belt  drive 
in  a  simple  and  convenient  manner. 

SUMMARY    OF    DIFFERENT   TYPES    OF    DEVICES. 
(Method  of  making  efficiency  tests  follows  this  list.) 
The  various  components  are  tabulated  below  in  the  order  of  their 
approximate  efficiencies  and  comparative  longevity. 
Pumps —  Length  of  Life. 

Efficiency.       (Comparative 

Val.) 

Reciprocating,  double    acting,    with    me- 
chanical valves 95%  100% 

Reciprocating,  double    acting,    poppet 

valves    87%  100% 

Reciprocating,  single  acting,  mechanical 

valves    80%  100% 

Reciprocating,  single    acting,     poppet 

valves    75%  100% 

Rotary — 

Two  impellor  type,  when  new 70%  45% 

Rotary  sliding  vane  type,  when  new....   62%  35% 

Turbine — 

Multi-vane  or  fan  (4-inch  vacuum)  35%  60% — 100% 

Injector,  Steam  or  Air — 

Steam  from  local  boiler 30%  100% 

Compressed  air  from  separate  compres- 
sor       24%  100% 

Motors — 

All  standard  makes  of  motors  have  the 
same  characteristics,  and  little  is  to  be 
said  on  this  point,  except  that  medium 
speed  motors  should  be  used  and 
speeds  should  be  kept  under  1,500  revo- 
lutions per  minute  in  general,  and  pref- 
erence given  to  slow  speed  motors. 
Electrical  efficiency  of  average  motors 

in  sizes  used  for  vacuum  cleaning  work  84%  100% 

Drives — 

Chain  drives,  of  Peerless  V,  Renold  Silent 

Chain,  Morse  and  similar  types 98%  100% 

Geared,  with  rawhide  pinion 90%  90% 

(But  is  noisier  than  silent  chain.) 
Leather  belt  .  .   75%— 85%       50% 


VACUUM  CLEANING  ENGINEERING  19 

Length  of  Life. 
Efficiency.       (Comparative 

Separators —  Val.) 

Automatic    or    Spiral    or    Cyclone    types 

(using  no  bags  or  screens)    100%  100% 

Bag   type,   using  canvas   sack   or   gauze 

screen  for  filtering  the  air 98%  90% 

Note. — When  sacks  are  not  cleaned  regu- 
larly   the    efficiency    drops    gradually. 

When  sacks  are  dirty,  average 70% 

Regulators  of  Vacuum — 

Vacuum     unloader   .(used    with     poppet 

valves)   . 75%  100% 

Vacuum  breaker,  regulating  type 70%  100% 

Hose — 

Rubber,  wire-reinforced,  smooth  bore  ....   75%  50% 

Steel,  flexible,  rubber  packed 70%  100% 

Note. — The  rubber  hose  is  a  trifle  more 
efficient,  owing  to  its  smooth  bore,  but 
the  flexible  steel  hose  will  wear  longer, 
and  the  actual  working  results  are  al- 
most identical,  and  the  steel,  being 
half  the  weight  and  twice  the  flexibility 
of  the  rubber,  make  it  the  more  easily 
handled.  The  steel  hose  is  preferable 
in  the  uncovered  state,  leaving  the  bare 
metal  exposed.  The  ends,  however, 
should  be  reinforced,  to  prevent  crack- 
ing at  the  operator's  handle  or  at  wall 
connection. 
Wall  Valves  for  Hose  Connection — 

Standard  1-inch  hose  flitting,  with  gas- 

keted  cap 100%  100% 

Automatic  flap  or  self-closing  valves 75%  50% 

A  standard  hose  thread  with  a  cap  and  rubber  or  leather  gasket 
affords  an  absolutely  air  tight  connection  when  hose  is  not  connected 
thereto,  and  will  last  indefinitely. 

Automatic  flap  valves  which  the  vacuum  draws  shut,  frequently  wear 
out  of  alignment  and  particles  find  lodgement  under  the  seat,  causing 
leakage.  This  type  is  not  as  desirable  unless  finish  requires  a  flush 
type. 

VACUUM    SCRUBBING. 
(See  Appendix.) 

General  Tests. 
The  pump  effiiciencies  of  positive  displacement  types  in  the  fore- 


20  VACUUM  CLEANING  ENGINEERING 

going  list  are  determined  by  accurate  test,  made  in  the  following  man- 
ner: 

Pump  Efficiency  Test — The  various  pumps  to  be  tested  are  con- 
nected in  turn  to  an  air-meter  (of  Queen  Co.  or  equal  manufacture) 
and  hose  or  pipe  connection  is  made  to  the  inlet  side  of  the  meter 
which  is  regulated  as  to  size  of  its  opening  until  the  vacuum  gauge 
stands  at  10  inches  of  mercury.  Under  these  conditions,  with  the 
pump  maintaining  constantly  10  inches  vacuum,  make  a  five-minute 
run  and  take  readings  on  the  air  meter  to  determine  just  how  many 
feet  of  air  pass  the  meter  per  minute,  at  the  Same  Time,  have  an 
assistant  take  the  current  consumption  reading  on  the  motor  and  at 
the  end  of  the  test  an  accurate  record  will  be  made  of  the  exact  cur- 
rent consumption  to  pass  a  given  quantity  of  air  at  a  10-inch  vacuum. 

If  several  machines  are  tested,  the  different  results  can  be  resolved 
down  to  the  current  consumption  per  foot  or  per  ten  feet  displace- 
ment and  the  various  pumps  then  compared  and  the  relative  efficiences 
shown.  If  the  tests  are  correctly  made,  the  results  wyill  approximate 
those  shown  in  the  above  table  of  pump-efficiencies. 

Testing  Plant  Operation — The  first  consideration  is  proper  cleaning, 
and  if  the  plant  does  not  properly  care  for  this  part  of  the  work,  the 
further  tests  of  the  apparatus  are  inconsequential. 

A  good  test  is  to  take  a  piece  of  carpet  having  a  good  nap,  and 
fill  it  with  small  particles  of  cotton  batting,  embroidery  silk  fluffed 
out,  also  threads,  feather  tips  and  similar  tenacious  material,  also 
a  quantity  of  plaster  of  paris,and  the  whole  tramped  into  the  carpet. 
The  carpet-renovator  should  then  be  applied  and  should  remove  this 
material  in  a  thorough  manner.  If  the  plant  will  remove  this  class 
of  material,  the  cleaning  may  be  deemed  satisfactory. 

Test  for  Separator  System — The  U.  S.  Government  call  for  the 
machine  to  clean  a  mixture  of  fine  sand,  powdered  charcoal  and 
white  flour,  approximating  at  least  two  quarts  scattered  over  a 
large  area  and  cleaned  from  various  outlets  without  allowing  any 
of  this  mixture  to  reach  the  pump.  This  test  is,  however,  usually 
waived  and  the  guarantee  on  the  effectiveness  of  separator  held  in 
its  stead. 

The  plant  should  run  smoothly  without  noise  or  vibration,  and 
should  not  show  any  movement  at  point  between  pump  base  and 
foundation. 

There  should  be  no  lost  motion  in  any  of  the  moving  parts  and 
the  plant  at  the  end  of  an  hour's  run  under  full  capacity  should  not 
be  warmer  at  any  of  its  moving  parts  than  a  temperature  which  can 
be  borne  by  the  hand. 

Oil  Consumption — As  soon  as  the  machine  has  had  an  opportunity 
to  wear  to  a  working  fit,  it  should  be  capable  of  operating  with  an 
oil  consumption  of  not  to  exceed  20  drops  of  oil  per  minute  to  any  one 
moving  part. 


VACUUM  CLEANING  ENGINEERING  21 

PIPING    SPECIFICATIONS. 

Standard  black  iron  pipe  or  electrical  conduit  may  be  used  for 
vacuum  piping  and  all  pipe  ends  must  be  reamed  to  the  full  diameter 
of  the  pipe  and  the  ends  squared  true.  All  rough  particles,  finns,  or 
burrs  must  be  removed  from  pipe  ends.  The  threads  should  be  run 
a  little  further  than  ordinary  pipe  work  to  allow  the  pipe  end  to  set 
securely  and  squarely  against  the  shoulder  of  the  recessed  fittings, 
which  are  to  be  used  throughout.  The  red-lead  or  joint  compound  is 
to  be  put  on  the  pipe  and  Not  Into  the  Fitting. 

The  fittings  used  on  the  entire  vacuum  piping  are  to  be  of  the 
recessed,  drainage  type  With  Long  Radius  Bends,  usually  known  as 
"Durham"  fittings. 

Long  sweep  tees  are  to  be  used  on  all  risers  at  each  floor  at  a 
level  determined  by  the  architect,  and  these  tees  are  to  be  bushed  to 
one  inch  and  a  one-inch  nipple  put  into  same  of  sufficient  length  to 
project  three-quarters  of  an  inch  beyong  the  finish. 

(NOTE — If  the  construction  is  such  at  any  particular  point  that  a  flush  type  outlet  is 
required,  then  specifications  should  state  that  at  such  point  the  tee  is  to  be  provided  with 
the  particular  fittings  necessary  to  the  proper  installation  of  the  flush  outlet  fuurished  by 
owner.) 

At  the  point  where  risers  project  through  into  basement  (or  lowest 
basement),  a  flanged  union  with  gasket  is  to  be  placed  close  to  ceiling, 
and  below  the  union,  with  a  nipple  should  come  a  long  sweep  tee,  the 
sweep  of  the  tee  being  in  the  natural  direction  of  air  flow  and  the 
unused  horizontal  end  of  the  tee  plugged  for  a  cleanout. 

On  all  horizontal  runs  of  over  thirty  feet,  flange  unions  must  be 
placed  at  thirty-foot  intervals  and  in  all  flange  unions  the  pipe  ends 
must  be  square  and  project  through  flush  with  the  face  of  the  flanges. 

(NOTE — With  this  construction,  all  portions  of  the  pipe  line  are  accessible  for  clean- 
ing in  case  of  a  stoppage.  The  flange  union  at  base  of  each  riser  allows  the  pipe  line  to 
be  broken  at  that  point  and  the  entire  riser  cleaned,  working  from  floor  to  floor,  and  the 
plugged  end  of  tee  on  the  horizontal  allows  horizontal  to  be  cleaned,  and  if  the  horizontal 
is  long  the  breaks  of  thirty  feet  will  render  the  work  easy  and  will  not  require  the  ser- 
vices of  any  skilled  help.) 

All  piping  should  be  brought  to  within  ten  feet  of  the  proposed 
location  of  the  vacuum  plant  and  all  horizontal  pipes,  if  more  than 
one,  should  be  brought  together  into  one  pipe  of  ample  capacity,  and 
at  least  as  large  as  the  inlet  pipe  connection  for  the  vacuum  pump. 
The  method  of  bringing  the  various  horizontals  together  shall  be  by 
means  of  standard  Durham,  fittings  with  flange  unions,  enabling  the 
horizontals  to  be  opened  at  the  ends,  or,  if  only  two  horizontals  come 
together,  a  double  long  sweep  tee  may  be  used  with  the  unused  open- 
ing plugged  for  cleanout. 

The  entire  piping  system  shall  be  so  installed  that  every  foot  of 
the  piping  system  shall  be  available  for  cleaning  in  case  of  a  stoppage. 

In  walls  or  concealed  places  where  it  is  necessary  to  make  bends 
in  the  pipe,  same  shall  be  done  by  Bending  the  pipe  in  every  instance 
possible  and  not  with  the  use  of  fittings. 

In   cases   where   it   is   necessary   to   lay   vacuum   pipes   in   cement 


22  VACUUM  CLEANING  ENGINEERING 

floors  or  horizontal  runs  in  walls,  cleanouts  should  be  provided  at 
least  every  forty  feet,  and  closer  if  possible,  either  by  means  of  a 
small  hand-hole  plate  giving  access,  to  a  plugged  cleanout,  or  the 
cleanout  may  be  brought  flush  with  the  surface  and  covered  with  a 
flush  deck-plate  or  similar  cover. 

Exhaust  Piping  requires  only  standard  fittings,  as  these  pipes 
will  contain  no  dirt.  The  exhaust  pipe  should  be  vented  into  the 
boiler  stack  or  in  fact  any  good  flue,  and  if  such  flue  has  a  boiler, 
furnace  of  other  heater  vented  into  it,  the  air  exhaust  should  be 
Brought  in  Above  the  Dampers  and  an  ell  placed  on  end  of  discharge 
pipe,  directing  the  blast  up  the  flue.  If  building  has  no  flue,  use 
muffler  and  oil  separator  and  vent  in  most  inconspicuous  place  or 
under  sidewalk — see  architect. 

Sizes  of  Vacuum  Pipes — Nothing  less  than  2-inch  pipe  should  be 
used  for  any  size  of  plant.  The  proper  method  of  calculating  pipe 
sizes  is  to  figure  the  exact  pipe  resistance  and  allow  for  a  drop  of 
not  over  2  inches  on  the  piping  system.  The  following  will  be  found 
adequate  for  general  use,  for  buildings  not  over  12  stories: 

For  one-sweeper  plants,  2-inch  piping,  both  risers  and  horizontals. 

Two-sweeper  plants,   2-inch  risers,  2-inch  horizontals. 

Three-sweeper  plants,  with  two  or  more  risers,  use  2-inch  pipe  for 
risers.  If  only  one  riser,  use  2^5  -inch  pipe  for  riser,  and  in  either  case 
2^ -inch  pipe  for  horizontals. 

Four-sweeper  plants,  2%-inch  risers  (if  only  one,  use  3-inch),  hori- 
zontal, 3-inch. 

Five  and  six-sweeper  plants,  2V£-inch  risers  (if  only  one  riser, 
3-inch) ;  horizontals,  3-inch. 

Seven  to  ten-sweeper  plants,  3-inch  risers  (if  only  one,  3^-inch; 
horizontal,  4-inch. 

The  piping  sizes,  of  course,  depend  entirely  on  the  number  of  open- 
ings that  will  be  in  use  on  each  riser  simultaneously,  and  as  the 
janitors  work  promiscuously  from  one  point  to  another,  it  is  well  to 
estimate  plenty  of  capacity  to  provide  for  cases  where  a  number  of 
janitors  are  all  using  the  same  riser  at  one  time. 

The  above  sizes  have  been  found  sufficient  for  all  ordinary  cases. 

Any  pipes  exposed  to  dampness  must  be  galvanized. 

Water  Connections  (all  galvanized) — A  three-quarter  water  connec- 
tion is  to  be  brought  to  within  ten  feet  of  the  location  of  the  machine. 
(Assuming  a  type  of  plant  or  separating  system  is  called  for  which  re- 
quires water.  This  water  connection  shall  be  controlled  by  valve  at 
branch  of  main  pipe. 

Sewer  Connection  shall  be  provided  (if  automatic  separator  speci- 
fied, 4-inch;  if  regular  wet  separator  system,  3-inch;  bag  type,  none 
required.)  Sewer  connection  to  be  provided  by  owner  and  connected 
to  by  contractor  installing  vacuum  plant. 


• 
VACUUM  CLEANING  ENGINEERING  23 


FOUNDATIONS. 

The  vacuum  pump  and  all  appliances  having  moving  parts  should 
be  supported  on  proper  foundations. 

If  the  machines  operate  without  vibration  and  are  of  medium 
power,  a  substantial  cement  basement  floor  is  ample,  providing  the 
construction  of  the  sub-base  of  the  machinery  is  such  that  it  will  keep 
the  moving  parts  well  clear  of  the  floor  and  out  of  water  which  might 
accumulate  on  the  floor. 

It  is  preferable,  however,  to  build  a  regular  foundation  of  cement 
at  least  six  inches  above  the  floor  on  plants  using  over  10  horsepower, 
and  if  the  cement  basement  is  already  in,  it  should  be  picked  into  to 
roughen  the  surface  sufficient  for  the  foundation  to  hold  and  the  foun- 
dation bolts  should  go  entirely  through  the  foundation  in  any  case. 

In  setting  foundation  bolts  in  a  foundation,  a  short  length  of  pipe 
should  be  placed  around  each  foundation  bolt  (the  bolts  having  large 
washers  at  their  lower  ends)  and  the  end  of  pipes  brought  flush  with 
the  upper  surface  of  the  foundation.  The  pipes  should  be  about  three 
times  the  diameter  of  the  bolts  and  the  space  between  bolt  and  pipe 
should  not  be  filled  until  after  the  machine  is  in  place.  This  con- 
struction allows  the  bolts  to  be  moved  in  any  position  to  accurately 
fit  the  holes  on  foundation,  and  after  the  machine  is  set  the  space  be- 
tween bolts  and  pipes  is  filled  in  with  soft  cement  and  allowed  to 
harden. 

A  template  of  the  foundation  should  always  be  made  when  the 
foundation  is  laid  out  and  holes  bored  corresponding  to  the  holes  in 
sub-base.  This  template  is  then  laid  over  the  bolts  after  they  are  in 
position  and  holds  them  in  place  while  the  cement  sets. 

For  fine  work,  a  grouting  is  run  between  foundation  and  sub-base 
after  the  machine  has  been  perfectly  leveled. 

WIRING. 

The  wiring  should  be  considered  in  advance,  and  if  the  architect 
desires  this  work  included  in  the  general  electrical  contract  (which 
is  usually  the  cheaper  method)  it  should  be  stated  in  the  electrical 
specifications  that  motor  circuit  should  be  brought  to  within  ten  feet 
of  the  proposed  location  of  the  vacuum  plant,  and  his  work  should  in- 
clude the  proper  fuses  and  switch  at  the  point  from  which  he  brings 
these  mains. 

The  architect,  by  figuring  3  1-3  horsepower  for  each  sweeper  he 
contemplates  using,  can  state  the  size  motor  to  be  wired  for. 

The  vacuum  contractor  should  then  be  required  to  make  all  con- 
nections from  the  point  within  ten  feet  of  his  machine,  furnish  neces- 
sary operating  switch  and  fuses  in  proper  cabinet  and  the  rheostat 
or  starting  device  for  his  motor  and  finish  the  work  in  a  workmanlike 
manner  in  accordance  with  local  rulings. 


24  VACUUM  CLEANING  ENGINEERING 

CONSIDERATIONS    IN    DRAWING   SPECIFICATIONS. 

Regardless  of  what  kind  of  equipment  is  to  be  installed,  the  capac- 
ity should  be  standard;  that  is,  the  capacity  of  the  vacuum  pump,  re- 
gardless of  its  type,  should  equal  at  least  75  cubic  feet  of  air  displace- 
ment to  each  sweeper,  the  vacuum  should  preferably  be  set  at  10 
inches  of  mercury  under  regular  operating  conditions,  and  the  horse- 
power at  not  less  than  3  horsepower  for  each  sweeper.  Then  the 
various  types  may  be  allowed  to  figure  their  respective  types  of  ap- 
paratus, providing  they  give  the  standard  required  for  good  cleaning. 
If  the  building  justifies  the  installation  of  a  high  grade  plant,  then  it 
would  be  advisable  to  specify  the  double  acting  reciprocating  type, 
with  mechanical  valves,  and  use  the  various  items  of  equipment  as 
specified  heretofore,  selecting  the  types  of  the  highest  efficiencies,  as 
shown  in  the  preceding  table.  Briefly,  specifying  Double  Acting  Re- 
ciprocating Pump,  Chain  Drive,  Automatic  or  Spiral  Type  Separators, 
and  requiring  slow  speed  machines.  A  list  of  specifications  should  be 
attached  pertaining  to  the  construction  of  parts,  which  each  bidder 
should  answer.  (See  specifications.) 

COMPARATIVE    COSTS    OF    MACHINES. 

A  good  reciprocating  type  plant  with  necessary  appliances  should 
cost  in  the  vicinity  of  $450.00  per  sweeper  capacity,  Not  Installed. 

A  rotary  plant  should  cost  about  $350.00  per  sweeper  capacity, 
both  being  based  on  the  same  capacity,  Not  Installed. 

These  figures  are,  of  course,  only  approximate,  and  will  depend 
largely  on  the  locations  and  distances  from  the  factories  supplying 
the  equipment. 


• 
VACUUM  CLEANING  ENGINEERING  25 


TYPICAL  SPECIFICATIONS 


In  presenting  specifications,  bidders  should  understand  that  the 
requirements  called  for  are  binding  and  that  substitutes  will  not  be 
considered. 

SPECIFICATION  FORM;  Specifications  covering  a  Vacuum  Clean- 
ing Plant,  for (Name  of  Bldg.) located  at 


Sealed  bids  will  be  received  by , 

at (Address) until (date) ,  for  a  vacuum 

cleaning  plant  capable  of  operating (Number)  sweepers 

simultaneously,  as  further  described  in  detail.  A  copy  of  these  specifi- 
cations is  to  be  signed  and  submitted  with  each  bid  and  will  consti- 
tute a  part  thereof. 

DELIVERY — Bidders  will  state  what  delivery  they  are  prepared 
to  make  (Or  specified  delivery  shall  be  called  for). 

CAPACITY — The  plant  shall  consist  of  one  unit  having  a  capacity 
of 

One  sweeper  residential,  60  cubic  feet  free  air  displacement. 

One  sweeper  commericial,  75  cubic  feet  free  air  displacement. 

Two  sweeper  commericial,  150  cubic  feet  free  air  displacement. 

Three  sweeper  commericial,  225  cubic  feet  free  air  displacement. 

Larger  plants  based  on  number  of  sweepers  multiplied  by  75  and 
shall  maintain  a  working  vacuum  of  (Residential  8  inches)  not  less 
than  10  inches  of  mercury. 

EXHAUSTER — The  exhauster  or  vacuum  producer  shall  be  (If 
high  grade  equipment  is  required)  of  the  reciprocating,  double  acting 
type  and  preference  will  be  given  to  mechanically  operated  valves. 

The  speed  of  exhauster  (if  larger  than  1  sweeper)  must  not  ex- 
ceed 250  revolutions  per  minute  and  must  deliver  the  specified  dis- 
placement and  vacuum  without  exceeding  this  speed. 

The  pump  must  be  constructed  in  such  a  manner  that  all  wearing 
parts  may  be  adjusted  in  a  convenient  manner  without  having  to  re- 
move any  parts  of  the  machine. 

The  Valves  may  be  mechanically  operated,  or  poppet  but  the  for- 
mer are  preferred  and  if  poppet  valves  are  used  they  must  be  re- 
movable by  a  valve  cage,  without  breaking  any  pipe  connection  and 
the  wearing  parts  must  be  capable  of  renewal. 

PISTON — must  have  at  least  two  rings  and  they  must  be  arranged 
so  that  joints  will  always  be  at  least  90  degrees  apart. 


26  VACUUM  CLEANING  ENGINEERING 

The  piston  must  have  a  very  slight  clearance  approximately  1-16 
inch  from  the  heads  at  end  of  strokes  and  the  valve  pockets  must  be 
small  as  possible  to  prevent  air  cushion. 

Piston  rod  shall  have  a  gland  of  ample  size  to  keep  air  tight  with- 
out undue  pressure  on  same. 

CROSS  HEAD — An  approved  design  of  cross  head,  running  in  double 
guides  shall  be  provided  and  means  of  adjusting  cross  head  and 
cross  head  pin  bearing  in  a  convenient  manner. 

JOURNALS — All  journals  shall  be  of  ample  size  to  hold  the  moving 
parts  rigidly  in  perfect  alignment,  without  undue  wear. 

LUBRICATION — Shall  be  provided  to  properly  lubricate  every 
moving  part  in  a  thoroughly  reliable  manner.  (If  mechanical  force 
feed  oiler  is  desired  to  lubricate  all  parts,  specify  same). 

TEMPERATURE  RISE— The  exhauster  should  be  so  designed  that 
the  temperature  rise  of  any  of  the  moving  parts  shall  not  exceed  100 
degrees  Fahr.  above  the  surrounding  atmosphere  when  run  for  at  least 
two  hours  at  full  load  and  must  be  capable  of  maintaining  these  con- 
ditions indefinitely  at  full  load  if  so  required. 

SUB-BASE — A  substantial  cast-iron  sub-base  shall  be  provided  on 
which  the  exhauster  and  motor  shall  be  mounted  in  perfect  and  per- 
manent alignment  and  means  shall  be  provided  thereon  for  taking 
up  slack  in  the  chain  drive.  If  required  by  architect,  holes  shall 
be  provided  in  the  sub-base  for  grouting. 

NAME  PLATE — The  machine  shall  be  provided  with  a  name  plate 
showing  the  Manufacturers  name;  number  of  revolutions  per  minute; 
amount  of  air  displaced  in  cubic  feet  per  minute;  also  the  bore  and 
stroke  and  the  number  of  horsepower  required  for  its  operation. 

(NOTE — If  a  cheaper  form  of  plant  is  desired,  omit  specifying  the  type  of  pump,  but 
require  the  full  capacity  and  vacuum  and  require  all  bidders  to  state:  Type  of  pump,  di- 
mensions of  cylinder  and  piston  (in  rotary  types),  the  displacement  and  guaranteed  vacuum 
with  rated  number  of  tools  in  simultaneous  operation  having  an  area  of  1  square  inch  at 
opening  of  each.) 

MOTOR — Shall  be  at  least Horsepower  (Number  of 

sweeper  capacity  multiplied  by  3)   and  shall  be  adapted  for  use  on 

Current  of volts, Cycles, Phase. 

It  shall  be  of  standard  make  and  architect  reserves  privilege  of  speci- 
fying the  make.  Motor  shall  be  of  medium  speed  and  shall  be  capable 
of  driving  the  exhauster  under  full  rated  load  indefinitely  without  un- 
due heating  and  shall  operate  without  objectionable  sparking. 

DRIVE — Between  motor  and  exhauster  shall  be  by  means  of  a 
Silent  Chain  Drive  of  Renold,  Peerless  V,  or  equal  and  at  least  six 
inches  of  extra  links  shall  be  provided  for  renewals.  Chain  drive 
shall  be  of  ample  size  and  have  at  least  50  per  cent,  margin  for  safety. 

(NOTE — In  residential  and  medium  size  plants  a  leather  belt  may  be  permitted.) 

SEPARATOR  SYSTEM — (For  sizes  1,  2,  and  3  sweeper) — Separator 
must  be  guaranteed  to  prevent  any  particles  of  dust  entering  the  ma- 


VACUUM  CLEANING  ENGINEERING  27 

chine  and  must  not  offer  excessive  resistence  to  air  passage.  Shell 
must  be  of  cast  iron  or  boiler  shell  construction  and  stand  on  cast 
iron  legs  of  sufficient  height  to  insure  easy  removal  of  dirt.  The  in- 
terior must  be  easily  accessible  and  bags,  if  used,  arranged  to  be 
easily  shaken.  A  spare  bag  must  be  furnished. 

FOR  SIZES  LARGER  THAN  3  SWEEPER— Separator  tanks  shall 
be  constructed  of  cast  iron  or  be  of  boiler  shell  construction  and  shall 
effectively  remove  all  particles  of  dust  and  dirt  from  the  air  before 
it  reaches  the  pump.  The  separator  system  shall  operate  Without 
Using  Bags  or  Screens  and  shall  be  of  either  the  spiral,  cyclone  type, 
slowing  the  air  current  until  the  dirt  drops,  or  shall  be  of  the  wet  type 
washing  the  air  under  water  effectively,  or  may  consist  of  both  types, 
or  of  Automatic  Self  Flushing  Type,  cleaning  entirely  by  washing  the 
air  with  water,  and  automatically  dumping  into  sewer  at  determined 
periods  without  attention.  The  internal  resistance  of  the  separating 
system  must  be  low.  Note — If  it  is  desired  to  use  the  equipment  for 
taking  up  scrub  water  then  the  Automatic  Type  Should  be  Specified, 
Self  Flushing. 

AUTOMATIC  CONTROL — A  simple  means  of  vacuum  control  shall 
be  provided  which  shall  decrease  the  current  consumption  in  direct 
proportion  as  sweepers  are  shut  off  and  the  efficiency  of  same  must 
be  at-  least  50  per  cent,  and  bidders  are  required  to  state  the  type 
regulator  they  propose  to  furnish. 

HOSE — The  hose  is  to  be  of  1  inch  internal  diameter  (Flexible 
Steel)  of  flexible  steel,  capable  of  being  bent  into  a  circle  approximately 
6  inches  in  diameter  and  packed  with  rubber.  Same  to  be  guaranteed 
air  tight  and  provided  with  approved  standard  threaded  hose  connec- 
tions. 

RUBBER — To  be  smooth  internal  bore,  wire  reinforced,  non-col- 
lapsible of  best  grade  and  provided  with  standard  hose  connections. 

Hose  shall  be  furnished  in  following  lengths 

(Specify  sufficient  to  allow  each  sweeper  to  reach  all  points  of  build- 
ing. Hose  comes  in  25  and  50  foot  lengths). 

HOSE  CONNECTIONS —  (Number) hose  connections 

shall  be  furnished  as  part  of  the  equipment  (The  number  required 
being  the  number  of  risers  multiplied  by  the  number  of  floors)  and 
these  shall  be  of  the  cap-and  chain  type,  having  gasketed  cap  and 
standard  hose  threads.  The  fitting  shall  be  nickle  (Or  brass)  highly 
polished. 

(NOTE — If  it  is  necessary  to  have  any  of  the  outlets  of  the  flush  type,  the  number 
of  each  should  be  mentioned,  as  the  flush  type  will  cost  a  trifle  more.  If  conditions  per- 
mit, the  cap-and-chain  type  is  the  most  reliable  and  satisfactory,  as  well  as  cheaper.) 

CLEANING  TOOLS— RENOVATORS— Carpet  renovators  must  have 
rounded  edges  that  will  not  cut  the  carpet  nap. 

The  renovators  shall  be  constructed  of  aluminum  as  far  as  possible 
for  lightness,  but,  where  subject  to  hard  wear,  they  shall  be  of  brass 


28  VACUUM  CLEANING  ENGINEERING 

and  nickeled.    All  parts  to  be  highly  polished  and  of  neat  appearance. 

Openings  through  the  renovators  should  be  one  square  inch  in  area 
at  all  points.  (For  more  than  one  sweeper):  Shut-off  valves  are  to 
be  provided  for  all  operating  handles  and  position,  (open  or  shut,) 
to  be  indicating.  Sets  of  renovators  shall  be  provided  for  cleaning 
carpets,  rugs,  bare  floors  of  all  kinds,  walls  and  ceilings  (The  latter 
should  be  swiveled)  and  upholstery  and  drapery.  An  extension  handle 
at  least  60  inches  long  and  coupling  should  be  provided  for  lengthening 
out  the  wall  and  ceiling  tools. 

(If  special  tools  are  required  they  should  be  enumerated  and  if  it  is 
desired  to  scrub,  a  number  of  squeegee  brushes  should  be  specified 
capable  of  taking  up  dirty  water). 

GUARANTEE — The  vacuum  contractor  shall  guarantee  the  pur- 
chaser immunity  from  any  annoyance  or  expense  on  account  of  matters 
pertaining  to  patent  or  infringement  proceedings  and  shall  also  guar- 
antee all  parts  of  the  equipment  to  be  perfect  in  design,  material  and 
workmanship  and  shall  replace,  free  of  expense  to  purchaser,  any  parts 
showing  defects  within  one  year  from  date  of  delivery. 

Vacuum  contractor  shall  also  guarantee  his  exhauster  to  comply 
with  all  the  requirements  herein  contained,  to  have  the  full  capacity 
called  for  and  operate  at  the  required  speed  and  with  the  power 
specified. 

INSTALLATION — If  it  is  desired  to  have  the  vacuum  contractor 
do  the  piping  and  installation  work  as  well,  then  specifications  should 
so  state  and  include — 

PIPING— See  preceeding  specifications  on  Piping,  which  may  be 
included  herein. 

ELECTRICAL  WORK — See  preceding  specifications  on  electrical 
work  and  entire  wiring  from  main  center  or  merely  connecting  up  from 
a  point  10  feet  from  the  motor  can  be  called  for  at  architect's  option. 

FOUNDATION — See  previous  specifications  covering  this  feature. 

ASSEMBLING— The  contractor  shall  see  that  all  details  and  acces- 
sories necessary  to  a  complete  system,  including  all  valves  and  ap- 
pliances are  supplied  and  properly  connected  and  the  machine  placed 
in  proper  running  order  ready  for  a  demonstration  and  at  such  time  it 
shall  be  turned  over  to  the  architect  or  his  representative  for  test 
and  acceptance. 

The  pipes  and  fittings  of  the  vacuum  plant  should  be  left  present- 
ing a  neat  appearance  and  all  pipes  within  twenty  feet  (Or  in  the  same 
room  if  small)  should  receive  a  coat  of  black  asphaltum  paint  (Unless 
different  color  is  preferred). 

All  dirt,  or  refuse  on  the  premises  resulting  from  the  work  of  the 
vacuum  contractor  shall  be  removed  and  any  damage  caused  by  or 
resulting  from  his,  work  shall  be  repaired  at  his  expense  and  he  shall 
leave  the  premises  in  as  good  condition  as  at  the  time  he  entered 
them. 


VACUUM  CLEANING  ENGINEERING  29 


APPENDIX 


COMPARISON    OF   DIFFERENT  SYSTEMS. 

The  question  of  a  suitable  vacuum  plant  is  usually  first  divided  be- 
tween a  comparison  of  high  vacuum  versus  low  vacuum,  and,  in  the 
writer's  opinion,  the  high  vacuum  systems  offer  greater  advantages  in 
every  way  than  the  low  vacuum. 

The  first  consideration  in  a  plant  is  to  get  proper  results,  and  there 
is  no  questioning  the  fact  that  high  vacuum  will  do  more  rapid  clean- 
ing of  tenacious  material,  and  remove  material  which  a  low  vacuum 
system  cannot  handle.  It  is  not  practicable  to  require  the  operator  of 
the  system  to  remove  lint  and  threads  by  hand,  and  the  machine  should 
be  capable  of  doing  it;  therefore,  the  high  vacuum. 

Another  important  matter  is  the  consideration  of  pipe  stoppages 
Removal  of  stoppages  in  pipes  is  a  costly  operation,  and  even  though 
the  pipe  line  may  be  installed  in  the  most  careful  manner,  it  is  most 
probable  that  stoppages  will  from  time  to  time  occur  in  the  bends  of 
the  pipe.  With  high  vacuum,  the  pipe  line  is  usually  self-cleaning, 
owing  to  the  fact  that  when  an  obstruction  occurs,  the  effect  is  similar 
to  closing  the  pipe  line,  and  the  vacuum  rises  to  a  high  point  (as  high 
as  27  inches  of  mercury  in  some  cases),  and  will  almost  invariably  pull 
the  obstruction  out  from  the  greatly  increased  vacuum.  With  low 
vacuum  systems,  the  vacuum  does  not  rise  when  an  obstruction  occurs, 
and  in  the  fan  types  actually  drops  off,  owing  to  the  fact  that  the  fan 
cannot  get  the  air  to  work  on,  on  which  its  vacuum  depends. 

High  vacuum  systems  employ  small  hose  of  1  inch  to  1*4  inches 
internal  diameter,  which  can  be  made  substantial  and  strong,  and  still 
be  light  and  flexible.  The  low  vacuum  systems  employ  hose  of  1% 
inches  to  2  inches  internal  diameter,  which,  if  made  in  a  substantial 
manner,  is  very  cumbersome  and  heavy,  or  if  made  very  light  is  not 
durable  for  commercial  service.  The  same  applies  to  the  tools  and 
handles.  In  making  light  enough  for  commercial  service,  strength  is 
sacrificed  to  make  the  devices  light. 

Low  vacuum  systems  are  of  the  multivane  or  centrifugal  fan  type, 
and,  as  there  is  a  strong  tendency  toward  cavitation  when  the  vacuum 
of  a  centrifugal  fan  reaches  one  inch  of  mercury.  The  efficiency  drops 
off  very  rapidly  above  this  point. 

For  high  vacuum  the  positive  displacement  pumps  are  required, 
and,  while  their  mechanical  friction  is  greater,  their  efficiency  is  much 
higher,  as  they  have  far  less  air  friction  and  their  mechanical  efficiency 
is  approximately  three  times  that  of  any  fan  type.  The  comparison  is 
very  similar  to  driving  an  automobile  by  an  air  propeller  as  against  a 
wheel  drive.  The  air  propellor  would  have  practically  no  mechanical 


30  VACUUM  CLEANING  ENGINEERING 

friction,  but  its  efficiency  developed  in  propelling  the  car  would  be  far 
less  than  a  positive  drive. 

Of  the  positive  displacement  pumps,  the  double  acting  reciprocating 
is,  of  course,  the  most  efficient  and  most  generally  understood  by 
mechanics,  and  is  to  be  preferred  where  first  cost  is  not  the  main 
consideration. 

CARE   OF   HOSE. 

The  vacuum  hose  should  be  handled  carefully,  to  insure  long  life.  It 
should  not  be  kinked,  and  when  not  in  use  siiould  be  coiled  in  a  three- 
foot  diameter  roll,  or  preferably  hung  on  hose  racks  or  reels. 

If  a  hose  stops  up,  it  should  be  turned  end  for  end,  and  the  end  at 
the  renovator  held  against  the  inlet  of  the  riser.  This  will  pull  the 
obstruction  back  in  the  direction  from  which  it  lodged,  and  will  in 
nearly  every  case  cause  an  immediate  clearance  of  the  stoppage. 

With  high  vacuum,  the  effect  may  be  increased  by  holding  the  hand 
over  the  open  end  of  the  pipe  until  the  vacuum  has  reached  a  high 
point,  and  then  suddenly  removing  the  hand,  allowing  the  impact  of  the 
air  to  strike  the  stoppage,  which  will  offer  a  further  means  of  removing 
the  obstruction. 

Hose  is  usually  provided  with  a  reinforcement  at  the  ends,  to  prevent 
kinking,  and  it  is  well  to  specify  a  reinforcement,  as  it  will  save  con- 
siderable damage. 

If  rubber  hose  is  used,  care  should  be  taken  not  to  allow  tacks  or 
pins  to  be  taken  up,  as  they  will  puncture  the  hose  and  cause  stoppages. 
Metal  hose  is  not  affected  by  sharp  objects 

If  the  vacuum  system  is  used  to  remove  scrub  water,  hose  should 
be  cleaned  at  the  close  of  the  work  by  holding  the  end  of  the  hose  in  a 
bucket  of  water  and  passing  about  two  buckets  of  water  through  the 
hose,  to  clean  out  all  dust,  and  then  allowing  the  air  to  draw  through 
the  hose  for  a  few  minutes  to  thoroughly  dry  it.  Once  a  week  it  is  well 
to  pass  a  little  lye-water  through  the  pipes,  and  immediately  follow  it 
with  clear  water,  and  dry  as  before. 

Metal  hose  appears  to  be  the  most  satisfactory  hose  where  subject 
to  hard  usage,  and  is  much  more  easily  handled. 

Practical  Use  of  Vacuum  Cleaning  in  Office  Buildings. 

Some  building  managers  use  the  vacuum  cleaning  plant  two  or 
three  times  a  week,  some  every  night  and  each  plan  has  its  advocates. 

It  is  the  writer's  opinion  based  on  careful  observation,  that  the 
most  satisfactory  method  is  to  vacuum  the  rooms  every  night — in  fact, 
dispense  with  brooms.  The  ^.nitor  crew  should  be  divided,  having 
a  certain  portion  of  the  force  to  "Pick  up,"  cleaning  the  large  particles, 
papers,  boxes  and  rubbish,  (In  fact  all  but  the  fine  particles  which 
the  vacuum  is  to  clean),  take  care  of  cuspidors,  etc.,  and  then  arrange 
for  the  vacuum  men  to  do  nothing  but  use  their  apparatus.  They  be- 
come skillful  and  can  accomplish  much  more  than  if  they  are  required 
to  stop  and  attend  to  several  kinds  of  work  and  also  waste  power  on 
the  sweepers  thereby. 


VACUUM  CLEANING  ENGINEERING  31 

A  proficient  vacuum  man  after  a  couple  of  weeks  work  should  clean 
the  floor  of  an  average  office  in  five  minutes  and  should  average  ap- 
proximately 32,000  square  feet  in  nine  hours.  The  transoms  in  the  cor- 
ridors should  be  cleaned  twice  a  week  with  the  wall  brush  and  this 
will  .require  about  15  minutes  to  an  average  floor. 

The  walls  and  ceilings  should  receive  a  thorough  cleaning  once 
every  four  or  six  months. 

HIGH   VACUUM— EFFECT   ON    RUGS  AND  CARPETS. 

Some  are  of  the  opinion  that  high  vacuum  (12  inches  or  more)  is 
injurious  to  the  nap  of  carpets  and  rugs.  This  is  not  a  fact  and  the 
use  of  a  vacuum  of  12  inches  every  night  will  actually  cause  less  wear 
on  the  rugs  than  a  6  inch  vacuum.  The  reason  is  as  follows. 

Wear  on  rugs  is  due  to  a  large  extent  from  sharp  edges  on  the 
renovators  which  shears  off  the  nap  from  purely  mechanical  means, 
independent  of  the  vacuum,  therefore  it  should  be  ascertained  in  all 
cases  that  the  edges  of  renovators  are  rounding  and  will  not  cut  the 
nap. 

As  a  vacuum  of  15  inches  is  equivalent  to  air  pressure  of  only 
7%  pounds  per  square  inch  it  is  ridiculous  to  think  that  this  could  in- 
jure a  carpet.  The  high  vacuum  pulls  out  dirt  with  one  application 
of  the  renovator,  whereas  low  vacuum  usually  requires  a  frequent  rub- 
bing back-and-forth  movement  to  loosen  the  dirt  before  the  low 
vacuum  can  pull  it  out — this  rubbing  causes  much  more  wear  than 
the  high  vacuum  which  will  pull  it  straight  out  by  passing  over  the 
nap  but  once.  This  is  particularly  the  case  where  mud  has  become 
caked  in  a  carpet — the  low  vacuum  plant  is  obliged  to  break  the  mud 
particles  up  by  repeatedly  running  over  it  and  in  so  doing  the  nap 
is  apt  to  crack  off  with  the  mud,  however,  the  high  vacuum  pulls  the 
mud  straight  off  the  ends  of  the  fibers  and  does  not  crack  them. 

Another  point  where  high  vacuum  is  a  saver  of  rugs  is  the  fact 
that  it  gets  the  grit  out  from  the  body  of  the  carpet — whereas  a  low 
vacuum  cannot  draw  it,  and  it  is  the  grit  in  a  carpet  continually  walked 
over  that  eventually  grinds  the  carpet  to  pieces.  Without  grit,  car- 
pets and  rugs  will  wear  almost  indefinitely. 

PORTABLE  VS.  STATIONARY  VACUUM   PLANTS. 

The  sphere  of  usefulness  of  the  portable  vacuum  plant  lies  entirely 
in  residence  work.  It  has  no  place  whatsoever  in  commercial  cleaning. 

In  an  office  or  public  building  the  cleaning  of  the  building  is  a 
commercial  proposition — it  is  done  on  a  wholesale  scale  and  it  should 
therefore  be  reduced  to  the  lowest  cost.  The  question  is — What  is  the 
most  expensive  item  in  cleaning  a  building?  The  answer  is  Time. 
Therefore  the  question  to  be  solved  is  How  to  Save  Time.  Compare 
six  janitors  using  6  portable  machines  of  say  l/s  horsepower  each, 
(If  they  are  of  the  ordinary  type),  as  against  6  janitors  each  with 
3  horsepower  at  his  disposal  and  nothing  to  move  but  his  hose.  The 


32  VACUUM  CLEANING  ENGINEERING 

stationary  plant  will  clean  in  one  tenth  the  time  and  do  five  times 
better  work  at  the  increased  speed.  The  current  consumption  to 
cover  a  given  area  may  be  about  equal  but  the  high  powered  plant 
will  cut  the  labor  item  into  a  small  fraction.  Furthermore  a  stationary 
plant  is  cheaper  than  a  portable,  besides  being  far  more  efficient,  for, 
if  the  same  power  in  portables  were  provided,  their  cost  would  run 
several  times  more  than  the  same  power  in  a  stationary  plant.  The 
reason  portables  appear  cheaper,  is  because  of  their  diminutive  power. 
A  stationary  plant  of  small  power  and  lower  cost  could  be  installed 
which  would  in  reality  do  far  better  work,  but  from  the  standard  of 
a  stationary, plant  would  be  too  small  to  consider.  The  portable  is  a 
plaything  when  considered  for  office  buildings  and  any  one  considering 
the  matter  seriously  cannot  fail  to  realize  it.  Some  portable  plants 
are  of  larger  size,  running  as  high  as  2  and  3  horsepower.  Of  these 
large  plants  there  is  naturally  no  fault  to  find  in.  effectiveness,  pro- 
viding they  approach  3  horsepower  to  each  machine,  but  they  then 
become  very  unwieldy  and  have  <to  be  carried  from  floor  to  floor 
on  elevators,  wasting  valuable  time  in  transporting  the  machine  around 
which  should  be  devoted  to  sweeping.  Further,  time  is  lost  in  connect- 
ing and  disconnecting  to  the  electric  supply.  « 

Another  feature  against  the  portable  is  the  unsanitary  feature  of 
drawing  the  air  from  the  under  surface  of  the  carpet  'where  the  dust 
has  settled,  and  discharging  this  dust  laden  air  back  into  the  room 
where  the  machine  is  operating.  This  dust  in  the  carpet  is  an  im- 
palpable powder  and  will  pass  through  the  mesh  of  an  ordinary  canvas 
sack  such  as  is  used  on  portable  separating  tanks.  A  dampened  cloth 
held  in  front  of  the  discharge  of  a  portable  machine  will  soon  be  dis- 
colored from  the  dirt  in  the  exhaust  air. 

REMOTE  CONTROL  SYSTEMS. 

It  is  sometimes  desirable  to  arrange  a  residential  system  so  that 
it  may  be  started  and  stopped  from  any  floor  in  the  house  and  for  this 
class  of  service  a  remote  control  switch  is  necessary. 

A  circuit  of  three  wires  should  be  run  from  the  location  of  the 
plant  to  each  of  the  control  points.  At  each  control  point  a  flush 
(or  exposed  type)  switch  is  installed,  for  direct  current  a  momentary 
contact  switch  and  for  alternating  current  a  4-way  switch.  These 
switches  when  operated  actuate  a  remote  control  switch  in  the  vicinity 
of  the  vacuum  plant,  which  in  turn  connects  the  power  to  the  motor, 
thereby  replacing  the  hand  starting  switch  usually  used.  If  direct 
or  polyphase  current  is  used,  the  remote  control  switch  automatically 
delivers  the  current  to  the  motor  in  proper  stages  to  insure  its  starting 
gradually.  If  single  phase  the  motor  is  usually  thrown  straight  accross 
the  line. 

A  most  satisfactory  line  of  automatic  starting  devices  is  manufac- 
tured by  the  Sundh  Electric  Co.,  of  New  York. 


INDEX 


Consideration  and  Comparison  of  Various  Types 3 

Establish  a  Standard  Capacity 3 

Principle  of  Operation  of  Vacuum  Cleaning 3 

COMPONENT  PARTS  OF  VACUUM  SYSTEM 4-16 

VACUUM  PUMPS 4-9 

Double  Acting  Reciprocating 4-5 

Single  Acting  Reciprocating 5-6 

Valve  Motions,  Reciprocating    -      6-7 

ROTARY  EXHAUSTERS   7-8-9 

Two  Impeller  . 7 

Vane  Type „ 8 

Turbine  and  Fan 8-9 

Injector ^ 9 

SEPARATORS .  . 9-12 

Automatic 9-10 

Adapted-to  Wet  Scrubbing See  Appendix 

Spiral  or  Cyclone 10-11 

Bag  Strainers 11-12 

POWER  SUPPLY 12-13 

Motors * 12 

Steam   Driven    13 

DRIVES 14 

Silent  Chain  .  . . 14 

Renold. 
Peerless. 

VACUUM  REGULATORS 14-15 

Regulator 14-15 

Unloader 15 

Breaker 15 

HOSE 15-16 

Metal  Hose 15 

Rubber  Hose 16 

Wall  Hose  Connections 16 

Exposed  Type — Cap  and  Chain 16 

Flush  Type 16 

MAIN   CONSIDERATIONS   IN   VACUUM    SYSTEM. 

REQUIREMENTS  TO   BE   DEMANDED    16-17-18 

Capacity  Required;  Vacuum  Required;  Rapidity  of 
Cleaning;  Power  Required;  Thoroughness  of  Clean- 
ing; Economy;  Quietness;  Speed;  Accessibility; 
Interchangeability;  Simplicity;  Longevity. 


INDEX. 


Summary   of  Different   Component    Parts   as   to    Efficiencies   and 

Length  of  Life   18-19 

Vacuum  Scrubbing    .". See  Appendix 

General  Tests  19-20 

Testing  Pump  Efficiencies .  20 

Testing  Plant  Operation   20 

PIPING  SPECIFICATIONS 21-22 

Foundations 23 

Wiring 23 

Considerations  in  Drawing  Specifications  24 

Comparative  Costs  of  Machines 24 

Typical  Specifications 25-28 

APPENDIX    29 

Comparison  of  Different  Systems — High  Vacuum  vs.  Low  Vacuum  29 

Care  of  Hose 30 

Practical  Use  of  Vacuum  in  Office  Buildings 30 

High  Vacuum;    Effect  on  Carpets 31 

Portable  vs.  Stationary  Plants 31 

Remote  Control  Systems 32 


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